Conventional waste tires may be crushed or pulverized for producing reclaimed rubber which is used in limited proportions as an extender to lower the cost of rubber products. It may be somewhat deleterious to the final physical properties of the rubber product, but it aids in the processing because it flows and extrudes readily. However, the reclaimed rubber generally accounts for a low percentage such as about 10% of rubber consumption in the United States. For environmental protection, it is necessary to treat the waste rubber tires not used in the above-mentioned reclaiming processes.
Several conventional cracking processes are therefore applied for treating the rapidly growing waste rubber tires for producing fuel oils and gases by cracking the waste rubber tires, of which a conventional process discloses a cracking reaction conducted at a high temperature of more than 1000.degree. C. under a high pressure of 3-30 kilograms per square-centimeter. However, such a conventional cracking process for cracking waste rubber products at high temperature and pressure may have the following drawbacks:
1. A high initial cost is required for installing the high pressure vessel at higher reaction temperature. PA1 2. Since many flammable gaseous products, such as: hydrogen, low-carbon hydrocarbon gases including methane, ethane, propane, butane, isobutane, butene, etc., may be produced during the cracking process, such flammable gases produced from the high temperature, high pressure reactor will be very dangerous or hazardous to the working environment in view of industrial safety factor. For instance, the hydrogen gas has an ignition temperature of 1085.degree. F. (585.degree. C.); methane of 999.degree. F. (537.degree. C.); ethane of 959.degree. F. (515.degree. C.), etc. They are all flammable, or easily explosive once leaked from the high-temperature cracking reactor and should be handled or treated very carefully, thereby increasing operation complexity and cost therefore. PA1 3. It will consume much energy to conduct the cracking reaction at higher temperature, thereby wasting valuable energy resources.
It is therefore expected to disclose a process for cracking waste rubber tires at lower temperature and pressure.